Add assertion to catch duplicated notes.

Sponsored by:	The FreeBSD Foundation


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272931 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Mark iscontrol(8) and iscsi_initiator(4) obsolete.

Differential Revision:	https://reviews.freebsd.org/D931
Reviewed by:	wblock@
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272932 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f